Traditional circuit breakers detect overcurrent conditions from electrical outlets downstream from the circuit breaker. Such breakers trip on detection of an overcurrent situation occurring from loads plugged into one of the downstream outlets. There are additional hazards including ground faults from a line conductor or a neutral conductor. Ground faults require ground fault circuit interrupter devices to detect and interrupt power to outlets. Another form of fault is an arc fault that may occur on the neutral and/or conductor lines between the outlets and the circuit breaker. Protection against arc faults is increasingly required in residential settings in the form of arc fault circuit interrupter (AFCI) devices. Such devices detect arcs in neutral and/or line conductors and remove power before such arcs can cause an electrical fire. AFCI protection may be located in outlets. Such outlets monitor and protect against faults with a set of contacts downstream of a detection module such as at the outlet itself. Faults are typically detected by the detection sensor in the outlet or outlets downstream of a conventional thermal-magnetic circuit breaker which breaks a contact in the AFCI outlet and thereby prevents current flow through the outlet and outlets downstream from the AFCI protected outlet.
With present devices for fault detection, the interruption by the AFCI outlet may only be triggered as a result of parallel arc faults detected downstream from the outlet or series arc faults. Thus, the outlet and corresponding detector cannot interrupt an upstream parallel arc fault (occurring between the outlet and the circuit breaker) because the contact interruption device at a known AFCI outlet cannot detect such faults and even if the contact interruption mechanism is triggered, the current would continue to flow through the fault. In a conventional electrical system, conventional circuit breakers cannot react quickly enough to such arc faults between the circuit breaker and an outlet. This poses a potential danger since the arc fault may be allowed to continue for some time before the circuit breaker interrupts power to the outlet.
Thus, a need exists for an arc fault detection and interruption system that detects parallel arc faults at points upstream from an outlet. There is a further need for an interruption system that interrupts power by tripping a circuit breaker mechanism upstream of the outlet. There is a further need for an arc fault detection system that uses existing components in an AFCI outlet for detection of arc faults upstream of an outlet.